Industrial truck



July 1, 1952 E. J. DUNHAM Erm. 2,601,931

INDUSTRIAL TRUCK INVENTOR.' ELMER J. DUNHAM ALFRED WAYNE GUNNIIC BY Wf E. J. DUNHAM ETAL July 1-, 1952 INDUSTRIAL TRUCK July 1, 1952 E. J. DUNHAM ET AL INDUSTRIAL TRUCK 5 Sheets-Sheet 3 Filed March 10, 1949 INVENTOR5: ELMER J. DUNHAM ALFRED WAYNE GUNNING BY July l, 1952 E. J. DUNHAM ETAL INDUSTR IAL TRUCK 5 Sheets-Sheet 4 Filed March lO, 1949 l INVENTORJ.' ELMER J. DUNHAM ALFRED WAYNE GUNNING BY m @l ATTYfs.

July l, 1952 E. J. DUNHAM ET AL INDUSTRIAL TRUCK Filed March 1o, 1949 5 Sheets-Sheet 5 INVENTOR.' ELMER J. DUNHAM ALFRED WAYNE GUNNING AT T Y5.

Patented July 1, 1952 Y INDUSTRIAL TRUCK Elmer J. Dunham and Alfred Wayne Gunning, Battle Creek, Mich., assignors to Clark Equipment Company, Buchanan, Mich., a corporation of Michigan Application March 10, 1949, Serial No. 80,738

6 Claims. (Cl. 214-82) This invention relates to industrial trucks and more particularly is directed to an industrial truck of the fork lift type having a mechanism associated with the load elevatingcarriage for discharging the load from the carriage, t this being commonly known as arpu'sher mechanism.

There have been numerous attempts heretofore to provide a pusher'mechanism forl pushing ofi loads carried on the forks or load supporting apron of the truck todischarge the same into a box car or the like, such mechanism being either designed for pushingthe loadrfoffa pallet carried by theforks A'or pushing the load-and the pallet olf together. 7

The present invention concerns itself more directly with the pusher mechanism per se and it may be used with a lift fork or apron construction on the load supporting carriage.

The present construction is adapted to be mounted upon a more or less conventional type of load supporting carriage, and is adapted for hydraulic actuation both in the pushing off movement and in the retracting movement. It primarily consists of a load engaging rack whichis disposed verticallywith respect to the load supporting fingers or apron and which is actuated through a linkage system pivotally mounted on a supporting member carried by the load supporting carriage under the influence of hydraulic piston means connected to one ofthe links.

The linkage means of'thepresent invention is capable of retraction to a folded position nesting within the supporting member, with the rack, disposed closely adjacent the Vheel of the forks or load supporting rapronyand is capable of extension to aposition'beyond the forward extremities of the forks.

One of the 'primary' objects of the present invention is to provide'a mechanism of this type vwhich can be extended to its fully extended posiit moves in substantially a straight horizontal line with the linkage mechanism being sufficiently sturdy to support it against the gravitational eiect, even when in fully extended position; and

to provide a sturdy non-cocking.action`.to pref vent any binding ofthenpivotal connections ,or the like. v j

Other objects and advantages of the present invention will appear more fully from the following detailed description which, taken in conjunction with the accompanying drawings, will disclose to those skilled in the art the particular construction and operation of a preferred form of the present invention.

In the drawings:

Figure 1 is a side elevational view of an industrial truck equipped with one form of pusher mechanism constructed in accordance with our invention -in retracted. position;

Figure 2 is a corresponding elevational View',

partly in section, of the rack mechanism of Figure l in extended position;

Figure 3 is a plan view of the rack mechanism of` Figure l in extended position;

Figure 4 is a side elevational view of another l ward driving wheels 6 and the rear steering wheels '1. The truck, adjacent its forward end, is provided with the vertical mast or upright assembly 8 pivotally mounted for fore and aft tilting movement adjacent its lowerend, and having a. suitable.` bracket connection 9 to a hydraulically controlled piston for controlling the tilting movement.

The driver seat is indicated at I0 and is disposed adjacent the steering column I2 which controls the movement of the rear steering wheels 1. The truck is provided with a power plant, such as an internal combustion engine having pump means associated therewith for developing uid underl pressure which is used not only for raising and lowering the load supporting carriage I4 guided for vertical movement within the mast 8, but also for actuating the tilting mechanism 9 and the rack actuating mechanism, indicated generally at I5.

Considering now the pusher mechanism in more detail, a conventional load supporting carriage I4 is provided and it preferably comprises a body member I9 mounted for vertical movement in the mast 8. The mast 8 is preferably formed of U-shaped channel members I6 rigidly connected at their upper ends by the cross member I1 and telescoping channel members I8 are mounted for 'sliding movement therein, and within which is mounted the body-member I9-of theY load supporting carriage. The body member I9 has forwardly projecting arms upon which are mounted vertically spaced face plates 22 which support forwardly projecting load engaging forks 23. These forks 23, at their upper ends, are provided with suitable bracket portions 24 hooking over the upper edge of the upper face plate 22, and each have a corresponding tongue member 25 engaging behind the lower edgeof the lower face plate 22.

In place of the forks 23 a solid supporting apron may be employed, or widened forks may be used for engaging the load to be carried by the truck. The particular type of load engaging means is not pertinent to the present invention and, therefore, the forks 23 are illustratedA to show a conventional type of load engaging mechanism employed with trucks of this type.

Also mounted upon the face plates 22 and secured thereto as by welding or the like, are supporting members 26 which are disposed adjacent opposite ends of the face plates 22 and extend vertically thereabove, being tied together at their upper ends by the transverse plate member 21, and at their lower endsl by a transverse plate member 2S. i

Extending rearwardly from the upper face plates 22 adjacent each side thereof, but within the confines of the supportingmembers 26, are brackets 29 which may be Welded or otherwise secured to the rear face of the upper face plate 22' and which, at. their upper ends,form a pivotal support as indicated 4at v3i), for the base 3,2 of a hydraulic .cylinder assembly, indicated generally at l5, and which has the head end thereof 33 provided with a suitable gland assembly for receiving the extending end Sli of a piston rod connected to the piston 35 disposed within the cylinder.

The piston rod 34, at its upper end, is connected through a Suitable clevis member 36 to a pivotal shaft 31, carried by the rearwardly extending end 38 of a crank member extending between the vertically extending supporting plates 26, andv bosses v43 welded or otherwise secured thereon,

which bosses have extending pivot studs 44 for mounting one end of a pair of links 45 and 46 thereon. The ends of the arms 42 opposite their pivotal connections to the shaft39, are each provided with a fitting 41, having a stud portion extending into the tubular end thereof and terminatingin a tongue portion 48 which is pivotally connected by means of the transverse pin 4.1).`- to the bifurcated end of a similar member 56, welded into the end of a second tubular arm member 52 to; provide arigid connection therebetween.

The. opposite endsA of the arms 52 are each provided with a fitting` 53 havingv an apertured end.v receiving the transverse shaft 54 carried by brackets 55v secured to the rear face of the rack member :indicated generally at 55. This rack membercomprises-a vertically extending plate or grid which has substantially thesame verticall extent. as the supporting plates 26 and which, at

its ends, is reinforced by means of side plates 51 and adjacent its upper and lower edges, has transversely extending plates 58 and the angle 59. The rack also is provided With intermediate reinforcing members 66 as shown in Figure-2.

A shaft 62 is rotatably supported at its opposite ends by suitable brackets 64 mounted upon the transverse plate 28 at the lower ends of the supporting plates 26. Tubular arms 63 are connected to the shaft 62 and are provided with fittings 65 similar to the fittings 41, except that they are bifurcated to receive the tongue ends of the fittings 66 carried by the tubular arms 61.V Transverse, pins 63 extend through the fittings 65 and 66'to provide a pivotal connection therebetween and these pins also provide for pivotallymounting of the opposite end of the links 45.

The tubular members 61 are similar to the arms 63 and at their opposite ends are each provided with a fitting 69 which is pivotally mounted between the lower end of a side plate 51 and a bracket 10 upon a transverse shaft 12 carried by the rack 56. The opposite end of each link 46 is pivotally connected to an arm 61 intermediate its ends by means of the stud 13. Thus it will be seen that the upper end of the rack and the supporting member are tied together through the pivotal connections of arms 42 and 52, while the lower end of the rack member is tied to the supporting member through the pivotal connections between arms 63 and 61. what might be .termed a pantograph type motion, with the links 45 and 46 interconnecting the tubular members 42 and 52 to the tubular members 63 and v61 and furtherproviding a limitingY 62 drawing the pivotal connection 66 toward the upper portion of the support 26 and conse-v quently, retractingV the lower end of the rack 56.

Due tothe interconnection of the links 45 and 46, this produces conjoint movement of the rack toward retracted position and into Va position -such as shown in Figure 1 withthe arms l42v and 63 being nested within the side plates 26 of the support.

Similarly, when the piston ismoved. downwardly in the cylinder. l5, it produces a corresponding rotation of crank'. 38 to rock arms '42 in al counter-clockwise direction, .thereby raising the pivotal point 49 and extending the rack 55,'j the arms 63 beingvv simultaneously rotated in a clockwise direction to apply substantially equal thrust to the top and bottom of the rack for maintaining it in a vertical plane while it is extending horizcntally.

As will be apparent from Figure l, the. arms 42' and 63 are nested substantially within the con.

Vfines of the support plate 26` when the rack is in retracted position, with the arms 52-and 61f-being substantially nested within vthe connes of the side members 51 ofthe rack, thereby Aallowing therack to approach closely the front edge of the support plates 26 and to be retracted into a ree` This provides tracted position adjacent the heels of the fork members 23. It will be noted that both of the pivotal connections 49 and 68 at this time are between the side members 26, thereby reducing, to a considerable extent, the spacial requirements of the arms when the rack is in retracted position.

Furthermore, due to the linkage arrangement,

.it will be seen that a similar support for the rack to prevent it from dropping as it is extended forwardly, is provided, thus providing a sturdjr support of the rack during its horizontal travel from the retracted position to the extending position. The linkage arrangement also provides for producing a relatively larger extending movement,

with a short movement of the piston assembly,. thus providing for rapid extension and contraction by reason of the use of a short stroke of the piston within the cylinder l5.

l The aforedescribed embodiment of our invention, while satisfactory for most instances lof use, is subject to the disadvantage that when the upper end of the rack 55 is engaged with a load to a greater extent than the lower portion of the rack, the linkage is such that the upper end of the rack will be caused to be tilted rearwardly. In the form of the invention shown in Figures 4 and 5, this disadvantage is overcome by the provisions of suitable bracing means indicated generally at 15 between the upper and lower shafts 39 and 62 extending between the side frame members 26 of the pusher supporting frame. The parts of the pusher mechanism of Figures 3 and 4 which are identical, or substantially so,

with the above described parts of the pusher mechanism of the embodiment shown in Figures 1 through 3 bear the same reference numerals, in view of which a further description of such parts is not believed to be necessary.

The bracing means 15, as shown in Figures 4 and 5, comprises a rst lever or crank arm 16 which is secured fast to the shaft 62 adjacent one end thereof inwardly of a side frame member 26 and substantially immediately below the crank arm 38 fixed to the tubular arm 42. The crank arm 38, as shown in this embodiment of our invention, is formed with a bracket member j 11 at a portion thereon disposed rearwardly of the upper shaft 62. A rod 18 is provided at its opposite ends with suitable clevis members 19 and 8U-, with the latter having adjustment means for adjusting the effective length of the rod, to provide for pivotally connecting the opposite ends of the rod to the crank arm 16 and bracket member 11.

The folding linkage operates in the manner previously described with the additional function served by the bracing means 15 of preventing backward movement of the upper portion of the rack under the circumstances above related. It will be observed that the bracing means 15 serves to connect the upper and lower shafts 39 and 62 to which, in turn, are fixed the tubular arms 42 and 63, respectively, so that the latter are moved conjointly in a positive manner upon movement of the rack againsta load and preventing collapsing of either of the two sets of arms 42 and 53 for the upper end of the rack 55, or of the arms B3 and 61 for the lower end of the rack. V

It will also be observed that in the last referred to embodiment of our invention, that the position of the connecting link 45' has been slightly altered in that the link 45 is arranged directly between fthe arm 42 and arm 61. The one end 6 of .theflink 45', as before, has pivotal connection with the arm 42 and the other end is pivotally connected toarm 61 as by means of a boss 43 and stud 44, as previously described, rather than having such other end pivotally mounted as on the stud 68 providing for pivotally connecting the arms 42 and 61 together.l This change is primarily an expedient in theY construction of the device, rand does not alter the operation of the pushermechanism as already described.

We areawaref that various changes may be madein certain details of the present constructions andtherefore, do not intend to be limited except as. defined by the scope and spirit of the appended claims.

We claim: y

'-1. A pusher'mechanism for an industrial truck havingcarriage means mounted thereon and includingload engagingmeans extending forwardly ofthe truck for supporting a load to be carried by the truck'comprising, a supporting frame adapted to .be mounted on said carriage means to extend transversely of said load supporting means closely adjacent the inner end thereof, said supporting frame comprising a pair of side frame members extending vertically adjacent opposite sides of said load supporting means, and

a pair of shafts extending horizontally betweenl said side frame members one adjacent each of the upper and lower ends thereof, a load engaging rack adapted to extend substantially vertically above said load supporting means, linkage means between said shafts and said rack comprising, first arm means mounted at one end on the shaft extending between the upper ends of said side frame members, second arm means pivotally mounted at one end adjacent the upper end of said rack, said first and second arm means extending downwardly toward each other and being pivotally connected together adjacent their other ends, athird arm means mounted at one A end on the shaft extending between the lower ends of said side frame members, fourth arm means pivotally mounted at one end adjacent the lower end ofsaid rack, said third and fourth arm meansextending upwardly toward each other and being pivotally connected together adjacent their other ends, and link arms extending between said rstand fourth arm means.

2. A pusher mechanism for an industrial truck having carriage means mounted thereon and including -load engaging means extending forwardly of the truck for supporting a load to be carried by the truck comprising, a supporting frame adapted to be mounted on said carriage means to extend transversely of said load supporting means closely adjacent the innerA end thereof, said supporting frame comprising a pair of side frame members extending vertically adjacent opposite sides of said load engaging means, and

a pair of shafts extending horizontally between mounted at one end on the shaft extending: be,- tween the lower ends of said side frame members, fourth arm means pivotally mounted at one end adjacent the lower end of said rack, said third and fourth arm means extending upwardly toward each other and being pivotally connected together adjacent their other ends, link means extending between said first and fourth arm means, crank arms connected to said pair of shafts, and rod means pivotally connected at the opposite ends thereof to said crank arms.

3. A pusher mechanism for an industrialtruck having carriage means mounted thereon and including load engaging means extending forwardly of the truck for supporting a load to be carried by the truck comprising, a supporting frame adapted to be mounted on said carriage means to extend transversely of said load supporting means closely adjacent the inner end thereof, said supporting frame comprising a Apair of side frame members extending vertically adjacent opposite sides of said load, engaging means, and a pair of shafts extending horizontally between said/side frame members one adjacent each of the upperl and lower ends thereof, a load engaging rack adapted to extend substantially vertically above said load supporting means, and linkage means between said shafts and said rack'comprising, first arm means mounted at one end on the shaft extending between the upper ends of said side frame members, second arm means pivotally mounted at one end adjacent the upper end of said rack, said rst and second arm means extending downwardly toward each other and being pivotally connected together adjacent their other ends, third arm means mounted at one end on a shaft extending between the lower ends of said side frame members, fourth arm means pivotally mounted at one end adjacent the lower end of said rack, said third and fourth arm means extending upwardly toward each other. and being pivotally connected together adjacent their other ends, link means extending between said first and fourth arm means, a rst crank means connected to the shaft between the upper ends of said side frame members and extending generally rearwardly of said supporting frame means, a second crank means connected to the shaft between the lower ends of said side frame members and extending generally forwardly of said supporting frame, and rod means pivotally connected at the opposite ends thereof to said crank means.

4. A pusher mechanism for an industrial truck having carriage means mounted thereon and including load engaging means extending forwardly of the truck for supporting a load to be carried by the truck comprising, a supporting frameA adapted to be mounted on said:v carriage-meansV tween said shaftsand said rack comprising, first arm means mounted at one end on the shaft exte :ding between the upper ends of said side frame members, second arm means'pivotally mounted at one end adjacent the upper end of said rack, said first and second arm meansextending downwardly toward each other and being pivotally connected together adjacent their other ends, third arm `means mounted at one end of a shaft extending between the lower-ends of said side frame lmembers, fourth` arm meansv pivotally mounted at one endadjacent the lower end of said rack', said third and'fourth arm means extending upwardly toward each other and being pivotally connected together adjacent their other ends, link means extending between said first and fourth arm means, a first crank means connected tothe shaft between 'theupper ends of said side frame members and extending generally rearwardly of said supporting frame means,a second crank means connected to the shaft between the lower ends of said side' frame members and extending generally forwardly of said supporting frame, rod means pivotally 'connected at the opposite ends thereof to said levers, and fluid pressure actuated means connected to said linkage means-for moving said rack substantially horizontally` forwardly and rearwardly above said load supporting means;

5. A pusher mechanism `for an industrial truck having carriage means mounted thereonrand including load engaging means extendingv forwardly of the truck for supporting a load to be carried by rthe truck comprising, a supporting frame adapted toV be mounted on said carriagemeans to extend-transversely of "said load supporting means closely adjacent the inner end thereof, a load engaging rack adapted-to extend substantially ver-` tically above said load supporting means, linkage means between said supporting frame and 'said rack comprising, first arm means mounted at one end to the upper end of said supporting frame, second arm means -pivotallymounted at one end adjacent the upper end' of said rack, said rst and-second arm` means'extending downwardly t0- ward each other and being pivotally connected together adjacent their other ends, 4third arm means mounted at one end adjacent the lower end of said supporting frame, fourth arm means pivotally mounted at one end adjacent the lower end of said rack, said-third and fourth arm means extending upwardly toward each other and being pivotally connected together adjacent their other ends, and link arms extending between said first and fourth arm means.

6. A pusher mechanism for an industrial truck having carriage means mounted thereon and including load engaging means extending forwardand Vsecond armmeans extending downwardly toward each `other and being pivotally connected together adjacent their other ends, third arm means mounted at oneend` adjacent the lower end of said supporting frame, fourth arm means pivotally mounted at one end adjacent the lower end of said rack, said third and fourth arm means extendingA upwardly toward each other and beingr pivotally connected .together adjacent their other' ends, link arms extending between said first and fourth arm means, firsty crank means connected to the upperend of said first arm means and extending generally rearwardly of said supporting frame, second crank means connected to ALFRED WAYNE GUNNING.

REFERENCES CITED The following references are of record in the 15 fue of this patent:

UNITED STATES PATENTS the lower end of said third arm means and ex- Nugr Blalnt al Jan Dgfelg tending generally forwardly of said supporting 1 567320 Davis Dec 29 1925 frame, rod means pivotally connected at the op- 5 2176636 Meach'ar-l v Oct' 17 1939 posite ends thereof to said iirst and second crank 2260947 Leach Oct 28' 1941 means, and fluid pressure actuated means con- 2418661 Palm Apr' 8 1947 nested to said linkage means for moving said rack substantially horizontally forwardly and rear- FOREIGN PATENTS Wardly above said load supporting means. 10 Number Country Date ELIVIER J. DUNHAM. 474,968

Germany Apr. 17, 1929 

